Searching the ocean floor for a super antibiotic

For premature babies, people with AIDS, cancer and transplant patients, or anyone else with a compromised immune system, fungal infections are a serious problem. They may sound like harmless ailments, but they can beat the best of the world’s antibiotics, and for many unlucky people, contracting a fungal infection can be deadly.

One fungal infection, Cryptococcus neoformans, is thought to be responsible for an estimated one million deaths each year worldwide, including some 600,000 in sub-Saharan Africa.

Now Israeli zoologists believe they may have an answer: the common marine sponge.

Scientists from the Department of Zoology at Tel Aviv University have identified several alternative antibiotic candidates among the unique compounds that help a sponge fend off predators and infections. Now, project leader Prof. Micha Ilan, and his graduate students are identifying, isolating and purifying those that could be the super-antibiotics of the future.

New drugs from the sea floor

The researchers have so far isolated thousands of bacteria and fungi, including a few hundred unique actinobacteria. So far, several dozen hold promise as new drugs.

“Resistance to antibiotics has become an unbelievably difficult challenge for the medical community,” says Ilan. “Sponges are known for hosting an arsenal of compounds that could work to fight infections. We’re now culturing huge amounts of microorganisms, such as actinobacteria, that live in symbiosis with marine sponges.”

Marine sponges are sedentary animals whose bodies consist of an outer thin layer of cells and an inner mass of cells and skeletal elements. Glued to the seafloor, they rely on the flow of water through their bodies to collect food and to remove waste.

Where teeth or shells don’t work

This has led to a unique adaptive response to enemies and competition. Sponges don’t have teeth, or shells, instead they protect themselves by building associations and partnerships with bacteria and fungi. TAU is tapping into these relationships – looking at the same chemicals that the sponge uses for defense as a means to fight infection in humans.

Drug developers have known for decades about the potential goldmine of pharmaceuticals in the marine environment, particularly among sedentary life like marine sponges. The problem, however, is that these compounds are found in very small quantities. Collecting and extracting large amounts of these chemicals would mean killing huge quantities of animals.

Instead, Ilan, who works in collaboration with Prof. Yoel Kashman and Prof. Shmuel Carmeli of TAU’s School of Chemistry, takes cultures from sea sponges with minimal damage to the natural environment. He then grows their symbionts and tests them in a “wet” laboratory. The methods Ilan has perfected can now be used by other scientists developing pharmaceuticals from marine sponges.

“Our research is unique in that we take both an agricultural and microbiological approach – not found often in the drug discovery community,” says Ilan.